This application is based on and claims priority to Japanese Patent Application No. 2000-353626, filed Nov. 20, 2000, the entire contents of which are hereby expressly incorporated by reference.
1. Field of the Invention
The present invention relates to a blow-by gas ventilation system for an engine. More specifically, the present invention relates to a blow-by gas ventilation system particularly adapted for use in a small watercraft.
2. Description of the Related Art
In most four-cycle engines, including those utilized in personal watercraft, a portion of the fuel/air charge delivered to the combustion chamber passes beyond the piston ring(s) and into the crankcase chamber, before being combusted, due to the extreme pressures generated in the combustion chamber. These fuel/air gases, or xe2x80x9cblow-byxe2x80x9d gases, are generally reintroduced into the induction system of the engine, through a ventilation system, to be combusted along with a fresh fuel/air charge. The blow-by gases tend to collect oil mist generated by the movement of engine components within the crankcase, such as the crankshaft and connecting rods.
It is generally desirable to separate the oil mist component of the blow-by gases from the fuel/air component so as to avoid undesired combustion of lubrication oil. An oil separation system is typically employed to separate these components and route the majority of the oil portion back to the lubrication system and route the fuel/air portion into the induction system. However, in the context of a personal watercraft, it is often not practicable to provide a separate system within the limited space of the hull to perform this function, without detriment to the size and/or layout of other engine components.
Further, when an oil separation system is employed in an engine arrangement, the blow-by gases are typically introduced freely into a plenum chamber of the engine. With such an arrangement, any oil mist that was not successfully separated from the blow-by gases may come into contact with the air filter element within the plenum chamber. Over time, the oil mist may clog the air filter element and have a negative effect on performance due to reduced airflow through the air filter element.
Accordingly, one aspect of the present invention is a blow-by gas ventilation system that separates an oil mist component of the blow-by gas from a fuel/air component and efficiently utilizes the available space within an engine compartment of a personal watercraft. Another aspect of the present invention provides a blow-by gas ventilation system that inhibits contact of oil mist remaining in the blow-by gas introduced into the plenum chamber of an engine from contacting the air filter element.
An aspect of the present invention is a watercraft including a hull defining an engine compartment. An internal combustion engine is disposed within the engine compartment. A propulsion device is driven by the engine of the watercraft. The engine includes an engine body defining a crankcase and at least one combustion chamber. A lubrication system supplies lubricant to at least the crankcase of the engine. An induction system is configured to guide air along an induction airflow path to the combustion chamber for combustion therein. The induction system includes a plenum chamber. A blow-by gas ventilation system allows blow-by gasses to move along a ventilation flow path from the crankcase to the plenum chamber. The blow-by gas ventilation system includes an oil separation chamber positioned within the plenum chamber. The ventilation flow path passes through the oil separation chamber.
Another aspect of the present invention is a watercraft having a hull defining an engine compartment. An internal combustion engine is disposed within the engine compartment and a propulsion device is driven by the engine. The engine includes an engine body defining a crankcase and at least one combustion chamber therein. A lubrication system supplies lubricant to at least the crankcase of the engine. An induction system is configured to guide air along an induction airflow path to the combustion chamber for combustion therein. The induction system includes a plenum chamber and a throttle body, which defines an intake port. A fuel delivery system delivers fuel to the combustion chamber and includes a fuel injector communicating with the intake port. A blow-by gas ventilation system for allowing blow-by gasses to move along a ventilation flow path from the crankcase to the plenum chamber. The blow-by gas ventilation system includes an oil separation chamber positioned within the plenum chamber. The ventilation flow path passes through the oil separation chamber.
A further aspect of the present invention involves a watercraft including a hull defining an engine compartment. An internal combustion engine is disposed within the engine compartment and a propulsion device is driven by the engine. The engine includes an engine body defining a crankcase and at least one combustion chamber therein. A lubrication system supplies lubricant to at least the crankcase of the engine. An induction system is configured to guide air along an induction airflow path to the combustion chamber for combustion therein. The induction system includes at least one throttle body and an inlet duct connected to the at least one throttle body. The throttle body and inlet duct at least partially defines an intake passage. A blow-by gas ventilation system includes an inlet communicating with the crankcase, an outlet communicating with the intake passage and a ventilation passage connecting the inlet and the outlet.
An additional aspect of the present invention involves a watercraft including a hull defining an engine compartment. An internal combustion engine is disposed within the engine compartment and a propulsion device is driven by the engine. The engine includes an engine body defining a crankcase and at least one combustion chamber therein. A lubrication system supplies lubricant to at least the crankcase of the engine. An induction system is configured to guide air along an induction airflow path to the combustion chamber for combustion therein. The induction system includes a plenum chamber. A blow-by gas ventilation system allows blow-by gasses to move along a ventilation flow path from the crankcase to the plenum chamber. Means are provided for separating lubricating oil from the blow-by gas and the means is positioned within the plenum chamber.
Another aspect of the present invention is a watercraft having a hull defining an engine compartment. An internal combustion engine is disposed in the engine compartment and a propulsion device is driven by the engine. The engine includes an engine body defining a crankcase and at least one combustion chamber therein. A lubrication system supplies lubricant to at least the crankcase of the engine. An induction system is configured to guide air along an induction airflow path to the combustion chamber for combustion therein. The induction system includes a plenum chamber, an air filter element and at least one throttle body. The air filter element is positioned upstream from the at least one throttle body. A blow-by gas ventilation system allows blow-by gasses to move along a ventilation flow path from the crankcase to the plenum chamber. The blow-by gas ventilation system includes an oil separation chamber. The air filter element, the at least one throttle body and the oil separation chamber are disposed within the plenum chamber and the at least one throttle body is positioned between the air filter element and the oil separation chamber.
Further aspects, features and advantages of this invention will become apparent from the detailed description of the preferred embodiment which follows.